1. Aviation Maintenance Management
Why We Have to Do Maintenance
Chapter 1

2. THIS DAY IN AVIATION January 28
1871 — The last balloon to leave Paris during the Persian siege takes off with orders for the French fleet to bring food and supplies to replenish the French capital, an armistice having been signed.
The flight of the General “Cambronne” ends a period of almost exactly 5 months during which the advantages of balloons were put to efficient use.

3. THIS DAY IN AVIATION
January 28
1945 — The Burma Road is reopened.

4. THIS DAY IN AVIATION January 28
1945 — The USAAF 8th AF observed its 3rd birthday with a 1,000 plane raid on Germany.

5. Aviation Maintenance Management
Introduction
Design & The Role of the Engineer
Role of the Mechanic
Types of Maintenance
Reliability & Redesign
Failure Rate Patterns
Other Maintenance Considerations
Summary

6. Introduction
Schedule pressures, parts shortages, equipment deficiencies, regulatory and agency compliance inspections, union pressures etc..
Technology advancements and diverse equip require perpetual training
Parts issues – no parts, cannibalization, aircraft on ground, weather conditions
Personnel issues – financial, family, substance abuse, late, no-show, vacations, trng, meetings – impact (touch labor)
Unscheduled Maintenance

7. Managerial Challenges
Aircraft out of service impacts –
crew training and readiness
Lost of revenue (no passengers – and maint/labor costs)
Loss of customer loyalty (customer is price based)
Intent of course not to make you an expert maintenance manager but to expose you to the various influences and the functions and techniques of the job
Knowledge is power

8. Modern Day Aircraft Maintenance
Aircraft require preventive or corrective maintenance at frequent intervals
Kind of operation; environmental conditions; storage facilities avail; age and construct of aircraft
Maintenance Man-hours per Flying hour (MMH/FH)
Cost to maintain a particular type of aircraft

9. Modern Day Aircraft Maintenance
Cost of ownership – fuel, wash, oil, tires etc…
Scheduled maintenance
Goal is to correct any deficiency before it occurs
Checks cost money – labor and parts, fluids costs and loss of passenger revenue when not flying
Total up all Maintenance associated costs subtract from revenue from aircraft and you get profit or loss

10. Design & Role of Engineer
We can design perfect systems on paper but we can not build perfect systems in the “real” world
Nothing is perfect
Good, Fast, Cheap
A design engineer may be limited from making the perfect system by technology or the state of the art within any facet of the design effort
Limited by ability, technique or economics
Economics may force a redesign with reduced tolerances, cheaper materials and gap between:
perfect and “perfect” realism

11. Role of the Mechanic
For the mechanic the gap between “perfect” & “perfect” realism always changes & predominantly for the worse
Components or systems tend to wear out from use or lack there of (time or environmentally related)
Misuse may cause premature deterioration or degradation of the system or even outright damage
The engineer’s responsibility is to design the system with as high degree of perfection within reasonable limits/constraints
The mechanic’s responsibility is to combat the gap between ideal & realism during the operational lifetime of the equipment

12. Two Types of Maintenance
Preventive Maintenance (PMs)
Performed at regular intervals – to prevent deterioration of the system to an unusable level and to keep it operational – often referred to as:
Scheduled Maintenance
Performed – daily, every flight, every 200 flight hours, or every 100 cycles (takeoff & landings)
Unscheduled Maintenance
Various, unpredictable intervals maintenance actions are required to restore a system that may require extensive testing, troubleshooting, adjusting, replacement, restoration, or complete overhaul of parts or subsystems

13. Maintenance Defined
Cost of Ownership and scheduled maintenance are 2/3 of equation
Unscheduled Maintenance – random failures
Reliability studies have led to MTBF (Mean Time Between Failure) – components / system guesstimated reliability factor
Induced failures – FOD, damage from servicing vehicles, maintenance malpractices
Inherent failures – delamination of composites, substandard bearings, inefficient seals etc.
No defect – A-799 or fault within tech data limits (require expenditure of maintenance resources)

14. Reliability & Redesign
“A measure of the probability that an item will survive to a specified operating age or time, under specified operating conditions, without a failure”
no amount of maintenance can be performed to increase the systems inherent level of designed in-level of perfection
Redesign
When the reliability decreases & a higher level of “perfection” is desired – redesign may take place
Needs to be weighed if the performance improvement justifies more maintenance & thus the increase in maintenance costs – ideally the opposite is true

15. Failure Rate Patterns (MTBF)
All systems or components fail at the same rate or exhibit the same patterns of wear out and failure
The maintenance performed is related to those rates and failure patterns (Table 1-1 pg. 10)
“Infant mortality” – early high failure rate in component’s life
“getting the bugs out”
Causes” poor design, improper parts, incorrect usage etc..
These characteristics of failure make it necessary to approach maintenance in a systematic manner to reduce peak periods of unscheduled maintenance
Several techniques have been designed to combat this:

16. Three Maintenance Management Techniques
Equipment redundancy, line replaceable units, & minimum aircraft dispatch requirements
Equipment Redundancy
Duplicate systems – primary and a backup (radios, navigation devices, flight control systems, computers)
Instrumentation within cockpit can signify status
Line Replaceable Units (LRUs) – black boxes
Designed to allow easy removal and replacement to reduce out of service timer of aircraft

17. Three Maintenance Management Techniques
Master Minimum Equipment List (MMEL)
Lists ALL equipment for the aircraft model – list is tailored to its MEL
Minimum Equipment List (MEL)
List of equipment that the aircraft may be inoperative but still allowed to fly as long as it does not affect the safety & operation of flight – Tailored to mission
Determined by manufacturer and sanctioned by the regulatory authority (FAA)

18. Three Maintenance Management Techniques
Minimum Equipment List (MEL)
Concept of the MEL is to allow the deferral of maintenance without upsetting mission requirements
Maintenance must be performed within some set of guidelines (1, 3, 10, or 30 days or cycles required) depending on operational requirements of the system
Pilot may always require or defer maintenance per the MEL
Maintenance MUST abide by decision…. (his call)
“Takes a college education to break it & a high school education to fix it.”

19. Minimum Equipment List (MEL)
Dispatch Deviation Guide (DDG)
Instructions for maintenance not necessary obvious to the mechanic – tying up cables, capping off connectors, taking circuit breakers out to prevent inadvertent power-up of equipment during flight while maintenance is being performed and any other precautionary steps that need to be taken
Configuration Deviation List (CDL)
List of information of equipment or panels etc. that may be missing or added per that aircraft model
All lists can be found in the aircraft logbook
3 techniques help minimize the workload and reduce service interruptions due to maintenance

20. Summary
The purpose of aircraft maintenance is to ensure the aircraft will remain airworthy throughout its operational life
Still haven’t reached perfection even with advances in technology
3 maintenance techniques help manage maintenance actions
Not all aircraft maintenance activities will be organized or operated in the same manner but the programs and activities will be the same